Anomalous Nernst Effect in the Dirac Semimetal Cd3As2

Dirac and Weyl semimetals display a host of novel properties. In Cd3As2, the Dirac nodes lead to a protection mechanism that strongly suppresses backscattering in a zero magnetic field, resulting in ultrahigh mobility (∼107 cm² V^-1 s^-1). In an applied magnetic field, an anomalous Nernst effect is predicted to arise from the Berry curvature associated with the Weyl nodes. We report the observation of a large anomalous Nernst effect in Cd3As2. Both the anomalous Nernst signal and transport relaxation time τtr begin to increase rapidly at ∼50 K. This suggests a close relation between the protection mechanism and the anomalous Nernst effect. In a field, the quantum oscillations of bulk states display a beating effect, suggesting that the Dirac nodes split into Weyl states, allowing the Berry curvature to be observed as an anomalous Nernst effect.